1. Field of the Invention
The present invention relates to a reel hub for winding a tape.
2. Description of the Related Art
As a method of fixing a beginning of a tape to a reel, there is a method with which a leader pin provided at the beginning of a tape is engaged to a hook part 31 of the leader block 30 as shown in FIG. 8A, and the leader block 30 is inserted into a slot formed in a reel hub. With this method, the leader block forms a part of a barrel of the reel.
A magnetic tape recording device has been improved to realize an increase in recording density, an extension of the length of the tape, and an increase in running velocity of the tape, for the purpose of implementation of higher-capacity recording and high-speed reading/writing. If those features described above are achieved, the length of the tape can be extended, and the reel can rotate at higher speed. When the extension of the length of the tape is achieved, the diameter of the reel with the total content of the wound tape is intended to be sustained by thinning the thickness of the tape.
When the length of the tape is extended, the number of windings of the tape on the reel increases, and a tape is wound harder on the reel, thus a leader block is pressed in a radial direction of the reel hub by the wound tape. One side of a hook part 31 of the leader block 30 is opened as shown in FIGS. 8A and 8B. Therefore, when the leader block 30 is pressed in the radial direction of the reel hub 32, open side of the hook part 31 is pushed into a slot 33 of the reel hub 32 deeply as shown in FIGS. 8B and 9, and a level difference is generated at a boundary of the leader block and the reel hub.
The level difference becomes a cause of a non-uniform winding of the tape particularly when the tape thickness is being thinner as shown in FIG. 9, and the non-uniform winding of the tape causes an non-uniformity of the tape running velocity, and further, it causes a reading/writing error of the high-density recorded data.
As a technique related to solving the problems described above, there is a “reel” disclosed in Japanese Unexamined Patent Publication 2003-203459 (Patent document 1). The invention disclosed in Patent document 1 is configured to eliminate the level difference from the boundary of the leader block and the reel hub and prevent the tape from being wound non-uniformly, by arranging a cover in a shape of a flat spiral spring on the reel hub and winding the tape on the cover.
In Patent document 1, the flat spiral spring is in a spiral shape when no load is applied, and deformed to be a circular shape to follow the shape of the reel hub when the tape is wound. Therefore, the force of the flat spiral spring to restore is required to be sufficiently smaller than the force applied by the tape to be wound.
However, if the elasticity of the flat spiral spring is too small, the spring cannot maintain its own shape when no load is applied, and the flat spiral spring 34 may be ruckled as shown in FIG. 10A or a tip edge part of the flat spiral spring 3 may be hung down as shown in FIG. 10B. If the tape is wound with such state, it causes a non-uniform winding.
That is, the invention disclosed in Patent document 1 is not configured to prevent the tape from being wound non-uniformly.